Windshield cleaning systems are already known, in which for the purpose of improving the effect of the washing system the washing liquid is supplied to jets which are arranged on the wiper arm-and-blade assembly and move in pendulum motion with it. In such an embodiment known from the AT-PS 3 13 083 the washing liquid is supplied through a bore in a wiper shaft, whereby for heating the washing liquid a resistance wire is inserted into the bore. Thereby resistance wire is loosely embedded into the washing liquid channel formed by the bore in the wiper shaft and consequently is in direct contact with the washing liquid so that the electric conductor must be perfectly isolated. The schematic illustration in this publication indicates that apparently these resistance wires are integrally realized from the voltage source up to the heating elements near the jet. This makes it much more difficult to assemble or dismount the wiper arm belonging to the wiper arm-and-blade assembly to or from the wiper shaft.